[PATCH 3/3] arm64: kasan: mte: remove redundant mte_report_once logic
Mark Rutland
mark.rutland at arm.com
Wed Jul 14 07:38:43 PDT 2021
We have special logic to suppress MTE tag check fault reporting, based
on a global `mte_report_once` and `reported` variables. These can be
used to suppress calling kasan_report() when taking a tag check fault,
but do not prevent taking the fault in the first place, nor does they
affect the way we disable tag checks upon taking a fault.
The core KASAN code already defaults to reporting a single fault, and
has a `multi_shot` control to permit reporting multiple faults. The only
place we transiently alter `mte_report_once` is in lib/test_kasan.c,
where we also the `multi_shot` state as the same time. Thus
`mte_report_once` and `reported` are redundant, and can be removed.
When a tag check fault is taken, tag checking will be disabled by
`do_tag_recovery` and must be explicitly re-enabled if desired. The test
code does this by calling kasan_enable_tagging_sync().
This patch removes the redundant mte_report_once() logic and associated
variables.
Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: Alexander Potapenko <glider at google.com>
Cc: Andrey Konovalov <andreyknvl at gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a at gmail.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Dmitry Vyukov <dvyukov at google.com>
Cc: Will Deacon <will at kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino at arm.com>
---
arch/arm64/include/asm/memory.h | 1 -
arch/arm64/include/asm/mte-kasan.h | 12 ------------
arch/arm64/kernel/mte.c | 12 ------------
arch/arm64/mm/fault.c | 15 +--------------
lib/test_kasan.c | 2 --
mm/kasan/hw_tags.c | 6 ------
mm/kasan/kasan.h | 7 -------
7 files changed, 1 insertion(+), 54 deletions(-)
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 7f4e6a923aa6..f1745a843414 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -243,7 +243,6 @@ static inline const void *__tag_set(const void *addr, u8 tag)
#ifdef CONFIG_KASAN_HW_TAGS
#define arch_enable_tagging_sync() mte_enable_kernel_sync()
#define arch_enable_tagging_async() mte_enable_kernel_async()
-#define arch_set_tagging_report_once(state) mte_set_report_once(state)
#define arch_force_async_tag_fault() mte_check_tfsr_exit()
#define arch_get_random_tag() mte_get_random_tag()
#define arch_get_mem_tag(addr) mte_get_mem_tag(addr)
diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
index 82fa4ac4ad4e..22420e1f8c03 100644
--- a/arch/arm64/include/asm/mte-kasan.h
+++ b/arch/arm64/include/asm/mte-kasan.h
@@ -131,9 +131,6 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag,
void mte_enable_kernel_sync(void);
void mte_enable_kernel_async(void);
-void mte_set_report_once(bool state);
-bool mte_report_once(void);
-
#else /* CONFIG_ARM64_MTE */
static inline u8 mte_get_ptr_tag(void *ptr)
@@ -164,15 +161,6 @@ static inline void mte_enable_kernel_async(void)
{
}
-static inline void mte_set_report_once(bool state)
-{
-}
-
-static inline bool mte_report_once(void)
-{
- return false;
-}
-
#endif /* CONFIG_ARM64_MTE */
#endif /* __ASSEMBLY__ */
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index c106d2ff8b1d..f6dae3e49d0f 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -22,8 +22,6 @@
#include <asm/ptrace.h>
#include <asm/sysreg.h>
-static bool report_fault_once = true;
-
#ifdef CONFIG_KASAN_HW_TAGS
/* Whether the MTE asynchronous mode is enabled. */
DEFINE_STATIC_KEY_FALSE(mte_async_mode);
@@ -138,16 +136,6 @@ void mte_enable_kernel_async(void)
}
#endif
-void mte_set_report_once(bool state)
-{
- WRITE_ONCE(report_fault_once, state);
-}
-
-bool mte_report_once(void)
-{
- return READ_ONCE(report_fault_once);
-}
-
#ifdef CONFIG_KASAN_HW_TAGS
void mte_check_tfsr_el1(void)
{
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 349c488765ca..9ae24e3b72be 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -309,24 +309,11 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
static void report_tag_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
- static bool reported;
- bool is_write;
-
- if (READ_ONCE(reported))
- return;
-
- /*
- * This is used for KASAN tests and assumes that no MTE faults
- * happened before running the tests.
- */
- if (mte_report_once())
- WRITE_ONCE(reported, true);
-
/*
* SAS bits aren't set for all faults reported in EL1, so we can't
* find out access size.
*/
- is_write = !!(esr & ESR_ELx_WNR);
+ bool is_write = !!(esr & ESR_ELx_WNR);
kasan_report(addr, 0, is_write, regs->pc);
}
#else
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 8f7b0b2f6e11..8be9d4b3b259 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -53,7 +53,6 @@ static int kasan_test_init(struct kunit *test)
}
multishot = kasan_save_enable_multi_shot();
- kasan_set_tagging_report_once(false);
fail_data.report_found = false;
kunit_add_named_resource(test, NULL, NULL, &resource,
"kasan_data", &fail_data);
@@ -62,7 +61,6 @@ static int kasan_test_init(struct kunit *test)
static void kasan_test_exit(struct kunit *test)
{
- kasan_set_tagging_report_once(true);
kasan_restore_multi_shot(multishot);
KUNIT_EXPECT_FALSE(test, fail_data.report_found);
}
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 2c6c6c6ddfa2..e4c16f6b6680 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -248,12 +248,6 @@ void kasan_free_pages(struct page *page, unsigned int order)
#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
-void kasan_set_tagging_report_once(bool state)
-{
- hw_set_tagging_report_once(state);
-}
-EXPORT_SYMBOL_GPL(kasan_set_tagging_report_once);
-
void kasan_enable_tagging_sync(void)
{
hw_enable_tagging_sync();
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 89587f762ab4..a8d3bb19b909 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -289,9 +289,6 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
#ifndef arch_enable_tagging_async
#define arch_enable_tagging_async()
#endif
-#ifndef arch_set_tagging_report_once
-#define arch_set_tagging_report_once(state)
-#endif
#ifndef arch_force_async_tag_fault
#define arch_force_async_tag_fault()
#endif
@@ -307,7 +304,6 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
#define hw_enable_tagging_sync() arch_enable_tagging_sync()
#define hw_enable_tagging_async() arch_enable_tagging_async()
-#define hw_set_tagging_report_once(state) arch_set_tagging_report_once(state)
#define hw_force_async_tag_fault() arch_force_async_tag_fault()
#define hw_get_random_tag() arch_get_random_tag()
#define hw_get_mem_tag(addr) arch_get_mem_tag(addr)
@@ -318,19 +314,16 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
#define hw_enable_tagging_sync()
#define hw_enable_tagging_async()
-#define hw_set_tagging_report_once(state)
#endif /* CONFIG_KASAN_HW_TAGS */
#if defined(CONFIG_KASAN_HW_TAGS) && IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
-void kasan_set_tagging_report_once(bool state);
void kasan_enable_tagging_sync(void);
void kasan_force_async_fault(void);
#else /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */
-static inline void kasan_set_tagging_report_once(bool state) { }
static inline void kasan_enable_tagging_sync(void) { }
static inline void kasan_force_async_fault(void) { }
--
2.11.0
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